What Is a Kilogram (kg)?
Definition
Kilogram (kg): The SI base unit of mass, symbol kg. Since 2019 it has been defined by fixing the value of the Planck constant. One kilogram is 1,000 grams.
The kilogram (symbol kg) is the base unit of mass in the International System of Units (SI). Since 20 May 2019 it has been defined by fixing the value of the Planck constant; before that, it was the mass of a platinum-iridium cylinder kept near Paris. The pound and the ounce are defined exactly in kilograms.
Where it appears in the formulas
1 kg = 1,000 g and 1 lb = 0.45359237 kg. The weight converter uses these exact definitions. For example, 1 kg is about 2.2046 pounds or 35.274 ounces, and 70 kg is about 154.32 pounds. The Planck constant is fixed at h = 6.626 070 15 × 10⁻³⁴ J s.
Weight and mass
What everyday language calls weight is mass, measured in kilograms. In physics, weight is a force, measured in newtons.